The state has numerous Buddhist centres at Amaravati, Nagarjuna Konda, Bhattiprolu, Mangalagiri, Ghantasala, Nelakondapalli, Dhulikatta, Bavikonda, Thotlakonda, Shalihundam, Pavuralakonda, Sankaram, Phanigiri and Kolanpaka. The golden beaches at Visakhapatnam, the one-million-year old limestone caves at Borra, picturesque Araku Valley, hill resorts of Horsley Hills, river Godavari racing through a narrow gorge at Papi Kondalu, waterfalls at Ettipotala, Kuntala and rich bio-diversity at Talakona, are some of the natural attractions of the state. Visakhapatnam is home to many tourist attractions such as the INS Karasura Submarine museum, Yarada Beach, Araku Valley, VUDA Park, Indira Gandhi Zoological Gardens. The weather in Andhra Pradesh is mostly tropical and the best time to visit is in November through to January. The monsoon season commences in June and ends in September, so travel would not be advisable during this period.